title: Intraoperative cardiac ultrasound examination using vector flow imaging.
abstract: Conventional ultrasound (US) methods for blood velocity estimation only provide one-dimensional and angle-dependent velocity estimates; thus, the complexity of cardiac flow has been difficult to measure. To circumvent these limitations, the Transverse Oscillation (TO) vector flow method has been proposed. The vector flow method implemented on a commercial scanner provided real-time, angle-independent estimates of cardiac blood flow. Epicardiac and epiaortic, intraoperative US examinations were performed on three patients with stenosed coronary arteries scheduled for bypass surgery. Repeating cyclic beat-to-beat flow patterns were seen in the ascending aorta and pulmonary artery of each patient, but these patterns varied between patients. Early systolic retrograde flow filling the aortic sinuses was seen in the ascending aorta as well as early systolic retrograde flow in the pulmonary artery. In diastole, stable vortices in aortic sinuses of the ascending aorta created central antegrade flow. A stable vortex in the right atrium was seen during the entire heart cycle. The measurements were compared with estimates obtained intraoperatively with conventional spectral Doppler US using a transesophageal and an epiaortic approach. Mean differences in peak systole velocity of 11% and 26% were observed when TO was compared with transesophageal echocardiography and epiaortic US, respectively. In one patient, the cardiac output derived from vector velocities was compared with pulmonary artery catheter thermodilution technique and showed a difference of 16%. Vector flow provides real-time, angle-independent vector velocities of cardiac blood flow. The technique can potentially reveal new information of cardiovascular physiology and give insight into blood flow dynamics.
authors.affiliation: 1Department of Radiology, Rigshospitalet, Copenhagen University Hospital, Denmark.
authors.forename: Kristoffer Lindskov
authors.initials: KL
authors.lastname: Hansen
authors.forename: Mads Møller
authors.initials: MM
authors.lastname: Pedersen
authors.forename: Hasse
authors.initials: H
authors.lastname: Møller-Sørensen
authors.forename: Jesper
authors.initials: J
authors.lastname: Kjaergaard
authors.forename: Jens Christian
authors.initials: JC
authors.lastname: Nilsson
authors.forename: Jens Teglgaard
authors.initials: JT
authors.lastname: Lund
authors.forename: Jørgen Arendt
authors.initials: JA
authors.lastname: Jensen
authors.forename: Michael Bachmann
authors.initials: MB
authors.lastname: Nielsen
mesh_terms: D000368:Aged; D001011:Aorta / Q000000981:diagnostic imaging* / Q000503:physiopathology; D001783:Blood Flow Velocity; D002302:Cardiac Output; D001026:Coronary Artery Bypass / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D016343:Monitoring, Intraoperative / Q000379:methods*; D011651:Pulmonary Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014463:Ultrasonography
keywords: Transverse Oscillation; blood flow; cardiac imaging; ultrasound; vector flow imaging